Kanske något sånt här:
SELECT
ROW_NUMBER() OVER(PARTITION BY [Group] ORDER BY Record) AS GroupSequence1,
RANK() OVER(PARTITION BY [Group] ORDER BY Record) AS GroupSequence2,
DENSE_RANK() OVER(PARTITION BY [Group] ORDER BY Record) AS GroupSequence3,
Table1.Group,
Table1.Record
FROM
Table1
GroupSequence1
, GroupSequence2
och GroupSequence3
ger dig den utdata du vill ha.